Importance of external cause coding for injury surveillance: lessons from assessment of overexertion injuries among U.S. Army soldiers in 2014.

Injuries are a barrier to military medical readiness, and overexertion has historically been a leading mechanism of injury among active duty U.S. Army soldiers. Details are needed to inform prevention planning. The Defense Medical Surveillance System (DMSS) was queried for unique medical encounters among active duty Army soldiers consistent with the military injury definition and assigned an overexertion external cause code (ICD-9: E927.0-E927.9) in 2014 (n=21,891). Most (99.7%) were outpatient visits and 60% were attributed specifically to sudden strenuous movement. Among the 41% (n=9,061) of visits with an activity code (ICD-9: E001-E030), running was the most common activity (n=2,891, 32%); among the 19% (n=4,190) with a place of occurrence code (ICD-9: E849.0-E849.9), the leading location was recreation/sports facilities (n=1,332, 32%). External cause codes provide essential details, but the data represented less than 4% of all injury-related medical encounters among U.S. Army soldiers in 2014. Efforts to improve external cause coding are needed, and could be aligned with training on and enforcement of ICD-10 coding guidelines throughout the Military Health System.